Stigmergy

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Stigmergy is a concept used to describe a special form of coordination of communication in a decentralized system that includes a large number of individuals. The individuals in the system do not communicate with one another directly, but only indirectly by modifying their local environment. What has been created together becomes, as it were, the trigger (see emergence ) of follow-up activities and general guidance on how to proceed with its creation.

A distinction is made between sematectonic and marker-based stigmergy . In sematectonic stigmergy, the current state of task fulfillment (for example the status and the characteristics of the nest building) influences the behavior of individuals communicating with one another; With marker- based stigmergy, on the other hand, it is task-independent markers ( e.g. odor and other messenger substances ) that are placed in the environment.

The term comes from the Greek words stigma (στιγμα) for marking and ergon (εργον) for work.

Working principle

The principle is based on the fact that a trace laid in an environment stimulates the execution of the next activity - by the same or another participant. In this way, subsequent activities tend to reinforce and build on each other, leading to the spontaneous emergence of coherent and apparently systematic activities. Stigmergy is a form of self-organization . It creates complex, possibly intelligent structures without any need for planning, control or even direct communication between those involved.

Stigmergy in nature

Stigmergy was first observed in nature. For example, ants communicate indirectly with each other when foraging by leaving pheromones along their streets : an ant colony is thus a stigmergic system.

Another example is the mounds made by termites . When building their highly complex structures, these insects also communicate by means of pheromones: each animal brings a particle of moist soil from its environment, provides the particle with pheromones and places it in the shared building. Termites are attracted to the pheromones of their colony's conspecifics, and it is therefore more likely that they will place their soil particle near a place where other termites have already left theirs. This gradually leads to the fact that columns, arches, tunnels and chambers are built. However, markers can become obsolete, diffuse, evaporate, etc., so that an effectively coordinated approach does not always result.

Stigmergy in technical systems

Stigmergy also has its place on the Internet, where many users ( agents ) communicate with one another by modifying their shared virtual environment ( commons-based peer production ). A direct exchange of messages would be dysfunctional. Rather, messages are stored locally and found by the agents involved, whose next actions they determine. However, the locally stored information can become out of date. An optimal solution is not always guaranteed.

Wiki technology is a good example of this . The content of a wiki is comparable to a termite mound: an individual leaves the germ of an idea (for example the beginning of an article in Wikipedia ), which in turn attracts other users. Building on an inconspicuous beginning, the initial concept is gradually developed into a complex structure of linked content without the need for direct contact between the processors, ie complexity can also arise through indirect coordination or indirect collaboration .

Another possible application is the optimization of transport routes in logistics . Here could e.g. B. Transport vehicles place markers (e.g. information chemicals) at stations they visit. The ability of the markers to diffuse or evaporate can also be used in a targeted manner.

Historical background

The term stigmergy was introduced in 1959 by the French biologist Pierre-Paul Grassé (1895–1985) with reference to the behavior of termites. He defined it as: stimulating workers through what they create . Stigmergy was later used in experimental research related to automation, multi -agent systems , swarm intelligence, and communication in computer networks.

literature

  • Pierre-Paul Grassé: La reconstruction du nid et les coordinations inter-individuales chez Bellicositermes natalensis et Cubitermes sp. La théorie de la stigmergie: Essai d'interprétation du comportement des Termites constructeurs. In: Insectes Sociaux 6 (Paris 1959), pp. 41-83.
  • Holger Kasinger, Jörg Denzinger, Bernhard Bauer: Decentralized coordination of homogeneous and heterogeneous agents by digital infochemicals , ACM Symposium on Applied Computing 2009, pp. 1223-1224.

Individual evidence

  1. ↑ "artisan brand," from the Greek: σήμα sema 'sign' and τέκτων Tekton "craftsman carpenter"
  2. ↑ https://www.informatik.uni-augsburg.de/de/lehrstuehle/swt/se/teaching/ws1112/soas/unterlagen/SOAS-Vorlesung-09_WS1112.pdf  ( page no longer available , search in web archives )@1@ 2Template: Toter Link / www.informatik.uni-augsburg.de
  3. ^ Peter Miller: Smart Swarm , Collins (2011), ISBN 978-0-00-738297-2 , p. 133

Web links